My sister, who is married and raising a daughter alone, was going on a business trip and asked me to look after my niece for a few days. I hadn't seen my niece for years, but she had grown not only taller but also larger breasts, and her uniform blouse was bursting with strain. I tried to Kokoro down by saying, "Hey, it's my niece!", but when I saw her innocently frolicking breasts, my male instincts prevailed over my reason and I got an incestuous erection. When my niece found my erect penis, she happily squeezed it between her breasts! She gave me a titjob with her firm, elastic breasts and I came instantly, and she kept sucking out my balls until they were empty!